Early Cambrian renewal of the geodynamo and the origin of inner core structure.

Paleomagnetism can elucidate the origin of inner core structure by establishing when crystallization started. The salient signal is an ultralow field strength, associated with waning thermal energy to power the geodynamo from core-mantle heat flux, followed by a sharp intensity increase as new thermal and compositional sources of buoyancy become available once inner core nucleation (ICN) commences. Ultralow fields have been reported from Ediacaran (~565 Ma) rocks, but the transition to stronger strengths has been unclear. Herein, we present single crystal paleointensity results from early Cambrian (~532 Ma) anorthosites of Oklahoma. These yield a time-averaged dipole moment 5 times greater than that of the Ediacaran Period. This rapid renewal of the field, together with data defining ultralow strengths, constrains ICN to ~550 Ma. Thermal modeling using this onset age suggests the inner core had grown to 50% of its current radius, where seismic anisotropy changes, by ~450 Ma. We propose the seismic anisotropy of the outermost inner core reflects development of a global spherical harmonic degree-2 deep mantle structure at this time that has persisted to the present day. The imprint of an older degree-1 pattern is preserved in the innermost inner core.

Aminated Graphene-Graft-Oligo(Glutamic Acid) /Poly(ε-Caprolactone) Composites: Preparation, Characterization and Biological Evaluation.

Biodegradable and biocompatible composites are of great interest as biomedical materials for various regeneration processes such as the regeneration of bones, cartilage and soft tissues. Modification of the filler surface can improve its compatibility with the polymer matrix, and, as a result, the characteristics and properties of composite materials. This work is devoted to the synthesis and modification of aminated graphene with oligomers of glutamic acid and their use for the preparation of composite materials based on poly(ε-caprolactone). Ring-opening polymerization of N-carboxyanhydride of glutamic acid γ-benzyl ester was used to graft oligomers of glutamic acid from the surface of aminated graphene. The success of the modification was confirmed by Fourier-transform infrared and X-ray photoelectron spectroscopy as well as thermogravimetric analysis. In addition, the dispersions of neat and modified aminated graphene were analyzed by dynamic and electrophoretic light scattering to monitor changes in the characteristics due to modification. The poly(ε-caprolactone) films filled with neat and modified aminated graphene were manufactured and carefully characterized for their mechanical and biological properties. Grafting of glutamic acid oligomers from the surface of aminated graphene improved the distribution of the filler in the polymer matrix that, in turn, positively affected the mechanical properties of composite materials in comparison to ones containing the unmodified filler. Moreover, the modification improved the biocompatibility of the filler with human MG-63 osteoblast-like cells.

Absence of a long-lived lunar paleomagnetosphere.

Determining the presence or absence of a past long-lived lunar magnetic field is crucial for understanding how the Moon's interior and surface evolved. Here, we show that Apollo impact glass associated with a young 2 million-year-old crater records a strong Earth-like magnetization, providing evidence that impacts can impart intense signals to samples recovered from the Moon and other planetary bodies. Moreover, we show that silicate crystals bearing magnetic inclusions from Apollo samples formed at ∼3.9, 3.6, 3.3, and 3.2 billion years ago are capable of recording strong core dynamo-like fields but do not. Together, these data indicate that the Moon did not have a long-lived core dynamo. As a result, the Moon was not sheltered by a sustained paleomagnetosphere, and the lunar regolith should hold buried 3He, water, and other volatile resources acquired from solar winds and Earth's magnetosphere over some 4 billion years.

Arrival and magnetization of carbonaceous chondrites in the asteroid belt before 4562 million years ago.

Meteorite magnetizations can provide rare insight into early Solar System evolution. Such data take on new importance with recognition of the isotopic dichotomy between non-carbonaceous and carbonaceous meteorites, representing distinct inner and outer disk reservoirs, and the likelihood that parent body asteroids were once separated by Jupiter and subsequently mixed. The arrival time of these parent bodies into the main asteroid belt, however, has heretofore been unknown. Herein, we show that weak CV (Vigarano type) and CM (Mighei type) carbonaceous chondrite remanent magnetizations indicate acquisition by the solar wind 4.2 to 4.8 million years after Ca-Al-rich inclusion (CAI) formation at heliocentric distances of ~2-4 AU. These data thus indicate that the CV and CM parent asteroids had arrived near, or within, the orbital range of the present-day asteroid belt from the outer disk isotopic reservoir within the first 5 million years of Solar System history.

Paleomagnetic evidence for modern-like plate motion velocities at 3.2 Ga.

The mode and rates of tectonic processes and lithospheric growth during the Archean [4.0 to 2.5 billion years (Ga) ago] are subjects of considerable debate. Paleomagnetism may contribute to the discussion by quantifying past plate velocities. We report a paleomagnetic pole for the ~3180 million year (Ma) old Honeyeater Basalt of the East Pilbara Craton, Western Australia, supported by a positive fold test and micromagnetic imaging. Comparison of the 44°±15° Honeyeater Basalt paleolatitude with previously reported paleolatitudes requires that the average latitudinal drift rate of the East Pilbara was ≥2.5 cm/year during the ~170 Ma preceding 3180 Ma ago, a velocity comparable with those of modern plates. This result is the earliest unambiguous evidence yet uncovered for long-range lithospheric motion. Assuming this motion is due primarily to plate motion instead of true polar wander, the result is consistent with uniformitarian or episodic tectonic processes in place by 3.2 Ga ago.

Paleomagnetism indicates that primary magnetite in zircon records a strong Hadean geodynamo.

Determining the age of the geomagnetic field is of paramount importance for understanding the evolution of the planet because the field shields the atmosphere from erosion by the solar wind. The absence or presence of the geomagnetic field also provides a unique gauge of early core conditions. Evidence for a geomagnetic field 4.2 billion-year (Gy) old, just a few hundred million years after the lunar-forming giant impact, has come from paleomagnetic analyses of zircons of the Jack Hills (Western Australia). Herein, we provide new paleomagnetic and electron microscope analyses that attest to the presence of a primary magnetic remanence carried by magnetite in these zircons and new geochemical data indicating that select Hadean zircons have escaped magnetic resetting since their formation. New paleointensity and Pb-Pb radiometric age data from additional zircons meeting robust selection criteria provide further evidence for the fidelity of the magnetic record and suggest a period of high geomagnetic field strength at 4.1 to 4.0 billion years ago (Ga) that may represent efficient convection related to chemical precipitation in Earth's Hadean liquid iron core.

Overall Survival of Patients With ALK-Positive Metastatic Non-Small-Cell Lung Cancer in the Russian Federation: Nationwide Cohort Study.

PURPOSE: The overall survival (OS) results in patients with ALK-positive metastatic non-small-cell lung cancer (NSCLC) have rarely been reported. The aim of this prospective-retrospective cohort study was to obtain real-world data on the use of crizotinib or chemotherapy in patients with ALK-positive metastatic NSCLC in Russia. PATIENTS AND METHODS: Patients with epidermal growth factor receptor-negative metastatic NSCLC were screened in 23 cancer centers. To be eligible, patients were required to have confirmation of ALK rearrangement. Patients were treated with crizotinib (250 mg twice daily; n = 96) or the investigator's choice of platinum-based chemotherapy (n = 53). The primary end point was OS. RESULTS: A total of 149 ALK-positive patients were included. Mean age was 53 years in both groups. Patients were predominately women (59%) and never-smokers (74%), and most patients had adenocarcinoma histology (95%). At a median follow-up time of 15 months, 79 of the 149 patients included in the analysis had died. Median OS from the start of treatment was 31 months (95% CI, 28.5 to 33.5 months) in the crizotinib group and 15.0 months (95% CI, 9.0 to 21.0 months) in the chemotherapy group (P < .001). The objective response rate was 34% in the crizotinib group. Among patients with brain metastasis, one complete response (6%) and five partial responses (31%) were achieved. Grade 3 adverse events were observed in three patients (3%) in the crizotinib group. CONCLUSION: The improved OS observed in crizotinib clinical trials in ALK-positive NSCLC was also observed in the less selective patient populations treated in daily practice in Russia. The use of standard chemotherapy in these patients remains common but seems inappropriate as a result of the effectiveness of newer treatments, such as crizotinib.

Ion Beam Nanostructuring of HgCdTe Ternary Compound.

Systematic study of mercury cadmium telluride thin films subjected to the ion beam bombardment was carried out. The evolution of surface morphology of (111) Hg1 - x Cd x Te (x ~ 0.223) epilayers due to 100 keV B+ and Ag+ ion irradiation was studied by AFM and SEM methods. X-ray photoelectron spectroscopy and X-ray diffraction methods were used for the investigation of the chemical compound and structural properties of the surface and subsurface region. It was found that in the range of nanoscale, arrays of holes and mounds on Hg0.777Cd0.223Te (111) surface as well as the polycrystalline Hg1 - x Cd x Te cubic phase with alternative compound (x ~ 0.20) have been fabricated using 100 keV ion beam irradiation of the basic material. Charge transport investigation with non-stationary impedance spectroscopy method has shown that boron-implanted structures are characterized by capacity-type impedance whereas for silver-implanted structures, an inductive-type impedance (or "negative capacitance") is observed. A hybrid system, which integrates the nanostructured ternary compound (HgCdTe) with metal-oxide (Ag2O) inclusions, was fabricated by Ag+ ion bombardment. The sensitivity of such metal-oxide-semiconductor hybrid structure for sub-THz radiation was detected with NEP ~ 4.5 × 10-8 W/Hz1/2at ν ≈ 140 GHz and 296 K without amplification.

Intrinsic paleointensity bias and the long-term history of the geodynamo.

Many geodynamo models predict an inverse relationship between geomagnetic reversal frequency and field strength. However, most of the absolute paleointensity data, obtained predominantly by the Thellier method from bulk volcanic rocks, fail to confirm this relationship. Although low paleointensities are commonly observed during periods of high reversal rate (notably, in the late Jurassic), higher than present-day intensity values are rare during periods of no or few reversals (superchrons). We have identified a fundamental mechanism that results in a pervasive and previously unrecognized low-field bias that affects most paleointensity data in the global database. Our results provide an explanation for the discordance between the experimental data and numerical models, and lend additional support to an inverse relationship between the reversal rate and field strength as a fundamental property of the geodynamo. We demonstrate that the accuracy of future paleointensity analyses can be improved by integration of the Thellier protocol with low-temperature demagnetizations.

Strong antibiotic production is correlated with highly active oxidative metabolism in Streptomyces coelicolor M145.

The Streptomyces genus is well known for its ability to produce bio-active secondary metabolites of great medical interest. However, the metabolic features accompanying these bio-productions remain to be defined. In this study, the comparison of related model strains producing differing levels of actinorhoddin (ACT), showed that S. lividans, a weak producer, had high TriAcylGlycerol (TAG) content indicative of a glycolytic metabolism. In contrast, the strong producer, S. coelicolor, was characterized by low TAG content, active consumption of its polyphosphate (PolyP) stores and extremely high ATP/ADP ratios. This indicated highly active oxidative metabolism that was correlated with induction of ACT biosynthesis. Interestingly, in conditions of phosphate limitation, the ppk mutant had TAG content and ACT production levels intermediary between those of S. lividans and S. coelicolor. This strain was characterized by high ADP levels indicating that Ppk was acting as an Adenosine Di Phosphate Kinase. Its absence resulted in energetic stress that is proposed to trigger an activation of oxidative metabolism to restore its energetic balance. This process, which is correlated with ACT biosynthesis, requires acetylCoA to fuel the Krebs cycle and phosphate for ATP generation by the ATP synthase coupled to the respiratory chain, resulting in low TAG and polyP content of the ACT producing strains.

Structural and Magnetoresistive Properties of Nanometric Films Based on Iron and Chromium Oxides on the Si Substrate.

Ultraviolet photons of KrF laser (248 nm) was used for the synthesis of nanometric films based on iron and chromium oxides (Fe2O3 - X (0 ≤ x ≤ 1) and Cr3 - X O3 - Y (0 ≤ x ≤ 2; 0 ≤ y ≤ 2)) with variable thickness, stoichiometry, and electrical properties. Film deposition was carried out on the silicon substrate Si < 100 > at the substrate's temperature T S = 293 K. X-ray diffraction and X-ray reflectometry analysis were used for the obtained structure characterization. Such a combined investigation reveals the composition and texture for samples investigated and provides useful information about layer thickness and roughness. Fe2O3 - X (0 ≤ x ≤ 1) nanometric films demonstrate the negative magnetoresistance in magnetic fields up 7 kOe. At the same time, for hybrid systems of the alternate layers Fe2O3 - X (0 ≤ x ≤ 1)/Cr3 - X O3 - Y (0 ≤ x ≤ 2; 0 ≤ y ≤ 2), the positive magnetoresistance as well as the magnetic hysteresis and magnetoresistivity switching effect in the low magnetic fields were observed.

Silicon Substrate Strained and Structured via Cavitation Effect for Photovoltaic and Biomedical Application.

A hybrid structure, which integrates the nanostructured silicon with a bio-active silicate, is fabricated using the method of MHz sonication in the cryogenic environment. Optical, atomic force, and scanning electron microscopy techniques as well as energy dispersive X-ray spectroscopy were used for the investigation of the morphology and chemical compound of the structured surface. Micro-Raman as well as X-ray diffraction, ellipsometry, and photovoltage spectroscopy was used for the obtained structures characterization. Ellipsometer measurements demonstrated the formation of the layer with the thicknesses ~700 nm and optical parameters closed to SiO2 compound with an additional top layer of the thicknesses ~15 nm and the refractive index ~1. Micro-Raman investigation detects an appearance of Ca-O local vibrational mode, and the stretching vibration of SiO4 chains characterized the wollastonite form of CaSiO3. A significant rise in the value and an expansion of the spectral range of the surface photovoltage for silicon structured via the megasonic processing was found. The concept of biocompatible photovoltaic cell on the base of Si\CaSiO3 structure for the application in bioelectronics was proposed.

Phosphate Homeostasis in Conditions of Phosphate Proficiency and Limitation in the Wild Type and the phoP Mutant of Streptomyces lividans.

Phosphate, as a constituent of the high energy molecules, ATP/GTP and polyphosphate, plays a crucial role in most of the metabolic processes of living organisms. Therefore, the adaptation to low Pi availability is a major challenge for bacteria. In Streptomyces, this adaptation is tightly controlled by the two component PhoR/PhoP system. In this study, the free intracellular Pi, ATP, ADP and polyP content of the wild type and the phoP mutant strain of S. lividans TK24 were analyzed at discrete time points throughout growth in Pi replete and limited media. PolyP length and content was shown to be directly related to the Pi content of the growth medium. In Pi repletion, ATP and high molecular weight (HMW) polyP contents were higher in the phoP mutant than in the WT strain. This supports the recently proposed repressive effect of PhoP on oxidative phosphorylation. High oxidative phosphorylation activity might also have a direct or indirect positive impact on HMW polyP synthesis. In Pi sufficiency as in Pi limitation, the degradation of these polymers was shown to be clearly delayed in the phoP mutant, indicating PhoP dependent expression of the enzymes involved in this degradation. The efficient storage of Pi as polyphosphate and/or its inefficient degradation in Pi in the phoP mutant resulted in low levels of free Pi and ATP that are likely to be, at least in part, responsible for the very poor growth of this mutant in Pi limitation. Furthermore, short polyP was shown to be present outside the cell, tightly bound to the mycelium via electrostatic interactions involving divalent cations. Less short polyP was found to be associated with the mycelium of the phoP mutant than with that of the WT strain, indicating that generation and externalization of these short polyP molecules was directly or indirectly dependent on PhoP.

Comparative proteomic analysis of Streptomyces lividans Wild-Type and ppk mutant strains reveals the importance of storage lipids for antibiotic biosynthesis.

Streptomyces lividans TK24 is a strain that naturally produces antibiotics at low levels, but dramatic overproduction of antibiotics occurs upon interruption of the ppk gene. However, the role of the Ppk enzyme in relation to the regulation of antibiotic biosynthesis remains poorly understood. In order to gain a better understanding of the phenotype of the ppk mutant, the proteomes of the wild-type (wt) and ppk mutant strains, grown for 96 h on R2YE medium limited in phosphate, were analyzed. Intracellular proteins were separated on two-dimensional (2D) gels, spots were quantified, and those showing a 3-fold variation or more were identified by mass spectrometry. The expression of 12 proteins increased and that of 29 decreased in the ppk mutant strain. Our results suggested that storage lipid degradation rather than hexose catabolism was taking place in the mutant. In order to validate this hypothesis, the triacylglycerol contents of the wt and ppk mutant strains of S. lividans as well as that of Streptomyces coelicolor M145, a strain that produces antibiotics at high levels and is closely related to S. lividans, were assessed using electron microscopy and thin-layer chromatography. These studies highlighted the large difference in triacylglycerol contents of the three strains and confirmed the hypothetical link between storage lipid metabolism and antibiotic biosynthesis in Streptomyces.

Gigantism in unique biogenic magnetite at the Paleocene-Eocene Thermal Maximum.

We report the discovery of exceptionally large biogenic magnetite crystals in clay-rich sediments spanning the Paleocene-Eocene Thermal Maximum (PETM) in a borehole at Ancora, NJ. Aside from previously described abundant bacterial magnetofossils, electron microscopy reveals novel spearhead-like and spindle-like magnetite up to 4 microm long and hexaoctahedral prisms up to 1.4 microm long. Similar to magnetite produced by magnetotactic bacteria, these single-crystal particles exhibit chemical composition, lattice perfection, and oxygen isotopes consistent with an aquatic origin. Electron holography indicates single-domain magnetization despite their large crystal size. We suggest that the development of a thick suboxic zone with high iron bioavailability--a product of dramatic changes in weathering and sedimentation patterns driven by severe global warming--drove diversification of magnetite-forming organisms, likely including eukaryotes.

Hemorrhagic fever with renal syndrome caused by 2 lineages of Dobrava hantavirus, Russia.

Dobrava-Belgrade virus (DOBV) is a European hantavirus that causes hemorrhagic fever with renal syndrome (HFRS); case-fatality rates in Balkan countries are as high as 12%. To determine causative agents, we examined 126 cases of DOBV-associated HFRS in central and southern European Russia. In central Russia (Lipetsk, Voronezh, Orel regions), outbreaks were caused by a DOBV variant (DOBV-Aa) carried by Apodemus agrarius. In southern Russia (Sochi district), where HFRS is endemic, HFRS cases were caused by a new DOBV variant (DOBV-Ap), found in A. ponticus, a novel hantavirus natural host. Both viruses, DOBV-Aa/Lipetsk and DOBV-Ap/Sochi, were isolated through Vero E6 cells, genetically characterized, and used for serotyping of the HFRS patients' serum. The clinical severity of HFRS caused by DOBV-Aa resembles that of HFRS caused by Puumala virus (mild to moderate); clinical severity of disease caused by DOBV-Ap infections is more often moderate to severe.

Regulation of ppk expression and in vivo function of Ppk in Streptomyces lividans TK24.

The ppk gene of Streptomyces lividans encodes an enzyme catalyzing, in vitro, the reversible polymerization of the gamma phosphate of ATP into polyphosphate and was previously shown to play a negative role in the control of antibiotic biosynthesis (H. Chouayekh and M. J. Virolle, Mol. Microbiol. 43:919-930, 2002). In the present work, some regulatory features of the expression of ppk were established and the polyphosphate content of S. lividans TK24 and the ppk mutant was determined. In Pi sufficiency, the expression of ppk was shown to be low but detectable. DNA gel shift experiments suggested that ppk expression might be controlled by a repressor using ATP as a corepressor. Under these conditions, short acid-soluble polyphosphates accumulated upon entry into the stationary phase in the wild-type strain but not in the ppk mutant strain. The expression of ppk under Pi-limiting conditions was shown to be much higher than that under Pi-sufficient conditions and was under positive control of the two-component system PhoR/PhoP. Under these conditions, the polyphosphate content of the cell was low and polyphosphates were reproducibly found to be longer and more abundant in the ppk mutant strain than in the wild-type strain, suggesting that Ppk might act as a nucleoside diphosphate kinase. In light of our results, a novel view of the role of this enzyme in the regulation of antibiotic biosynthesis in S. lividans TK24 is proposed.

Formation of insoluble magnesium phosphates during growth of the archaea Halorubrum distributum and Halobacterium salinarium and the bacterium Brevibacterium antiquum.

Stationary phase cells of the halophilic archaea Halobacterium salinarium and Halorubrum distributum, growing at 3-4 M NaCl, and of the halotolerant bacterium Brevibacterium antiquum, growing with and without 2.6 NaCl, took up approximately 90% of the phosphate from the culture media containing 2.3 and 11.5 mM phosphate. The uptake was blocked by the uncoupler FCCP. In B. antiquum, EDTA inhibited the phosphate uptake. The content of polyphosphates in the cells was significantly lower than the content of orthophosphate. At a high phosphate concentration, up to 80% of the phosphate taken up from the culture medium was accumulated as Mg(2)PO(4)OH x 4H(2)O in H. salinarium and H. distributum and as NH(4)MgPO(4) x 6H(2)O in B. antiquum. Consolidation of the cytoplasm and enlargement of the nucleoid zone were observed in the cells during phosphate accumulation. At phosphate surplus, part of the H. salinarium and H. distributum cell population was lysed. The cells of B. antiquum were not lysed and phosphate crystals were observed in the cytoplasm.